This invention relates in general to a rectangular package which is formed from a blank and, in particular, to a blank of paperboard material which is capable of being formed into a package which is capable of holding a liquid, semi-solid, or solid product and may be provided with a separate opening tab for enabling the top portion of the package to be completely opened. The invention also concerns a particular method of making the package.
Paperboard materials are becoming increasingly popular as a packaging material, especially in the food industry. A sheet of paperboard material used to form a package typically includes a main structural layer of paper to provide strength and rigidity to the associated package. In some instances, a layer of aluminum foil can be adhered to one surface of the paperboard to serve as a barrier layer against the passage of contaminants into the package.
Generally, both surfaces of the paperboard are then coated with a heat sealable thermoplastic material. While a number of specific constructions are known, it is generally accepted practice to fold a precut and pre-scored blank of paperboard material into a predetermined configuration, and to apply pressure and heat to certain contacting surfaces of the folded blank to form a package.
Many types of paperboard packages capable of holding a liquid and provided with some type of opening have been proposed. Examples of such packages are disclosed in U.S. Pat. Nos. 3,347,444; 4,317,518; 4,520,929, and U.S. Pat. No. 4,546,884, and in U.S. Pat. No. 5,250,018, which is assigned to the assignee of this application, which are incorporated herein by reference thereto. While the packages disclosed in these patents have been found to be satisfactory for certain packaging applications, there continues to be a need in the industry for a variety of rectangular paperboard packages which are capable of being hermetically sealed and which can be produced economically.